Computing vertex connectivity: New bounds from old techniques

The vertex connectivity K of a graph is the smallest number of vertices whose deletion separates the graph or makes it trivial. We present the fastest known deterministic algorithm for finding the vertex connectivity and a corresponding separator. The time for a digraph having n vertices and m edges is O(min(pow3(K)+n,K.n)m); for an undirected graph the term m can be replaced by K.n. A randomized algorithm finds K with error probability 1/2 in time O(n.m). If the vertices have nonnegative weights the weighted vertex connectivity is found in time O(K'.n.m.log(pow2(n)/m)) where K'